Devices of various designs for lowering or raising a bridge during erection by means of a laying rail or a launching support have been known.
Thus, a bridge-erecting device, which has a drivable hydraulic cylinder with bearing plate and is held pivotably in the launching support, has been known from DE 28 46 182 A1. This hydraulic cylinder can be driven from the vehicle only via flexible hydraulic double lines with numerous coupling points between the individual launching supports, between the launching support and the different bridge sections, as well as between the vehicle and bridge sections, where the hydraulic pump is located. In the case of a collapsible bridge according to DE 31 38 853 C2, the support feet are folded out and hydraulically extended at the top of the launching support when the ramp part of the launching support is already located on the laying device and is advanced forward. The disadvantage is that operating personnel must cross over to the other bank over the bridge, which has not yet been laid, in order to operate the hydraulic system.
A bridge-erecting device for collapsible, transportable bridges, which has a hanging-down ground support at its projecting front end of the first laying rail section, has been known from DE 31 06 140 C2. This support has, at its lower end, a transversely extending foot, which is attached in an articulated manner and is provided with two support plates, which are also arranged in an articulated manner. A hydraulic cylinder, which is operated by hand, is arranged between the foot and the support leg of the ground support.
A device for lowering and raising bridges, especially collapsible, stationary bridges, is designed according to DE 37 19 508 C2. According to this disclosure the tip part of the launching support is adjustable in height by a hydraulic cylinder by means of an adjusting device forming a hinge parallelogram.
The principal disadvantage of these prior-art laying systems is the relatively heavy metal construction, by which the cross section of the launching support or laying rail is unfavorably affected.
The support plates in these laying systems must be designed such that the supports and laying devices will have a secure hold even under unfavorable ground conditions.